1. Field of the Invention
The present invention relates to an FTTH (Fiber To The Home) systems, and more particularly to a TDM (Time Division Multiplexing) frame applicable for digital broadcast data transmission in an FTTH (Fiber To The Home) system and a method for transmitting and receiving the TDM frame.
2. Description of the Related Art
A broadcast services and communication services are currently provided independently to the home or office. Research on convergence of broadcast services and communication services is presently being conducted. Bi-directional HFC (Hybrid Fiber Coaxial) type system, and IP (Internet Protocol)-based system using an xDSL (x Digital Subscriber Line) network are known broadcast/communication systems. A system based on an FTTH (Fiber To The Home) is also be considered.
Because the broadcast/communication convergence system of the bi-directional HFC type uses a coaxial cable, there is a problem in that the bandwidth is limited due to a physical limit of the coaxial cable and a complex modulation scheme, such as a subcarrier modulation scheme, must be used. Moreover, as the IP-based broadcast/communication convergence system using the xDSL network that performs a transmission operation in units of packets, it is difficult for the broadcast service to be seamlessly provided. In this case, since a process for linking the packet units is required, time delay is incurred and a real-time broadcast service cannot be appropriately provided, such that QoS (Quality of Service) cannot be satisfied. In addition, because the xDSL uses a copper line as a transmission medium, there is a drawback in that a bandwidth is limited due to physical properties of the copper line.
For this reason, the broadcast/communication convergence system using the FTTH system is popular because of a wider bandwidth and faster transmission speed.
The broadcast/communication convergence system using the FTTH system uses a TDM transmission technique for convergence of the broadcast service and communication service. Here, the TDM transmission technique is to ensure a plurality of time slots is available and that there is appropriate transmission of desired data at each time slot. If a processing operation associated with the time slots is appropriately performed, broadcast streams can be seamlessly transmitted.
Where a digital broadcast based on the FTTH system is transmitted using the TDM transmission technique, synchronization between transmission data units is an important factor. In particular, transmission clock synchronization for a digital broadcast can be different for each broadcast provider or broadcast program. Where various clock signals are inputted, a need exists for a TDM frame format capable of synchronizing the different clock signals.